IN VIVO AND IN VITRO EFFICACY OF NIGELLA SATIVA AQUEOUS EXTRACT ON BLASTOCYSTIS HOMINIS

Metronidazole (MTZ) was the most widely accepted treatment for Blastocystis hominis (B. hominis) with high treatment failure rate, resistance and potential mutagenic and carcinogenic effects so there is urgent need to find out new, effective and safe treatment against B. hominis. The present research aimed to evaluate the therapeutic effect of the aqueous extract of Nigella sativa (NS) at different doses on B. hominis in vitro and in vivo in comparison to MTZ as a control drug. Isolates of B. hominis were obtained from patients complaining of diarrhea and abdominal pain. Isolates were cultured in egg diphasic medium (LE) for in vitro study and to adjust proper inoculating dose for in vivo study. The aqueous extract of NS at concentrations of 100 & 500 µg/ml showed a potent lethal effect on B. hominis isolates in vitro. Caecal tissue of experimentally infected and treated mice with two different doses of NS (250 & 500 mg/kg/d) were examined histopathologically and compared with that of mice infected and treated by two doses of MTZ (62 & 125 mg/kg/d) as control drug and Infected untreated mice as negative control group. Histopathological examination of infected untreated group showed all pathological degrees in the caecal tissue while infected treated one showed remission of pathological changes especially with higher dose (500 mg/kg). Present study proved that N. sativa had inhibitory effect on B. hominis in vitro and prevented cytopathic effect in infected mice inoculated orally with B. hominis.

Evaluation of polymerase chain reaction on amniotic fluid for diagnosis of congenital toxoplasmosis

The present study assessed sensitivity and specificity of PCR targeting P30 gene in diagnosis of congenital toxoplasmosis using amniotic fluid samples. A total of 358 pregnant women in their first trimester of pregnancy, most of them were asymptomatic while the others suffered lymphadenopathy, fever and/or malaise. The serum sample from each woman was screened for Toxoplasma-specific ELISA IgM & IgG. Sero-negative females were then screened in 2nd & 3rd trimesters for sero-conversion. Amniocentesis was performed to seropositive and sero-converted women. Detection of Toxoplasma DNA in AF was done by animal inoculation and PCR targeting P30 gene. 85/358 women were sero-positive for Toxoplasma. Congenital infection was detected in 14/85 fetuses by MI. One mouse had tachyzoite in peritoneal exudate while other 13 showed cysts in histpathological sections of mice. PCR test targeting P30 gene was positive in 13 with additional four fetuses, only PCR gave positive results, and serologic follow-up of suspected fetuses (17) by IgM ELISA confirmed congenital toxoplasmosis. Sixteen cases of congenitally infected newborn were a symptomatic. One was clinically diagnosed (ventricular dilatation) by the ultrasound. The PCR drastically changed the diagnostic repertoire for prenatal diagnosis. The sensitivity and specificity of PCR targeting P30 gene on AF samples were 92.9% & 94.4% respectively while positive predictive value (PPV) was 76.5%, and negative predictive value (NPV) was 98.5%. Its disadvantages were in fact that negative result cannot exclude acute infection, and thus must be confirmed by MI and it is also an expensive technique.

Evaluation of the nitric oxide activity against Blastocystis hominis in vitro and in vivo

The effect of exogenous nitric oxide (NO) on growth, viability and ultra-structural of B. hominis was assessed in vitro by sodium nitrite (NaNO2) in 0.6 mM, 0.8 mM & 1 mM concentrations. The viability of B. hominis was identified using neutral red stain. The role of NO as an endogenous oxidant was assessed by identifying its level in cecum tissue, ileum tissue, blood and stool elutes of mice infected with B. hominis symptomatic human isolates using reactive nitrogen assay compared to control. In vitro study revealed that NaNO2 inhibited the growth and decreased viability of B. hominis with minimal lethal concentra-tion dose 1 mM on the 4th day while, minimal effects were detected with 0.6 and 0.8 mM. Transmission electron microscopy study proved that apoptotic-like features were observed in growing axenic culture of B. hominis upon exposure to NaNO2. These changes were not only found on the vacuolar (central body) form but also they were detected on granular, multi-vacuolar and cyst forms. In vivo study proved that high levels of NO were found in infected mice compared to low changes in control group. The high levels were in cecum tissue particularly. The mean levels of NO among infected mice were 211.8 +/- 20.7 microM in cecum, 90.4 +/- 11.6 microM in ileum, 60.1 +/- 4.7 microM in blood and 63.6 +/- 7.3 microM in stool elutes while, the mean levels of NO in control mice were 70.2 +/- 3.1 in cecum, 67.8 +/- 4.7 microM in ileum, 30.9 +/- 4.2 microM in blood and 28.1 +/- 2.9 microM in stool elutes. The differences were statistically highly significant. NO-donor drugs proved useful in treatment and increase the host resistance to B. hominis.

Effect of exogenous adminstration of antioxidants on Blastocystis hominis in vivo

The effect of exogenous administration of antioxidant (Anttox) on the course of B. hominis in experimentally infected mice was studied. B. hominis isolates were obtained from 10 gastrointestinal symptomatic adult patients. Three groups of 30 infected mice (3/isolate) were used. GI was untreated infected, GII was treated by antox for 4 weeks after infection diagnosis (treatment strategy), and GIII antox treated by for 4 weeks before infection (prophylactic strategy). Mild pathological changes were detected on 13.4%, 19.9% & 86.8% of mice in Gs I, II & III, respectively. Moderate pathological changes were found in 29.9%, 26.6% & 6.6% of mice in Gs I, II & III, respectively. While, the majority of severe pathological changes were in Gs I & II (56.7% & 53.5%) as compared to GIII (6.6%). Meanwhile, 86.8% of mice in GIII had B. hominis forms > 10/high power field compared to 3.3% in Gs I & II, respectively. Although 19.8% of mice in GII were positive for B. hominis by direct smear, no growth resulted in vitro and all the forms were non-viable by using neutral red stain. All the differences were statistically significant. So, antioxidant exacerbated B. hominis intensity but it decreased the pathological changes.